Environmental toxicants have been implicated in a number of developmental disorders. Unfortunately, the health effects subscribed to these exposures occurs long after the actual exposure. For fetuses, exposure estimates are particularly difficult due to the difficulty of obtaining tissue for analysis. Biological markers for low to moderate exposure to environmental toxicants, as well as biological markers for adverse neurodevelopmental effects of these exposures would allow earlier identification and intervention for affected infants, recognition of women at risk for exposure, and facilitate research on dose-response relationships between environmental exposures to mixtures of toxicants and to other known developmental neurotoxicants (ethanol and nicotine) and neurodevelopmental outcome. Meconium, the first stool passed by a newborn, has been used to establish exposure to drugs of abuse. The presence of environmental toxicants in meconium has been reported. Research in the investigators laboratory has shown a significant associations between the quantity of fatty acid ethyl esters (ethanol metabolites) in meconium and both maternal self-reported low to moderate levels of drinking during pregnancy and the infants performance on the Bayley Scales of Infant Development at 6, 12, and 24 months of age. This proposal seeks to address the hypothesis that environmental toxicants as well as nicotine and ethanol metabolites in meconium are useful biological markers for exposure to developmental neurotoxicants, and may indicate infants at risk for poor neurodevelopment, by achieving the following 2 specific aims: 1) Determine a methodology to accurately analyze and compare 6 classes of neurotoxicants in a single sample of meconium. 2) Describe the presence of these neurotoxicants in a cohort of 400 infants (Project 1) and characterize their relationship to more traditional maternal and environmental measures obtained as part of Project 1. Project 1 will aim to characterize the meconium measures with neurodevelopmental outcome. These studies will utilize the patient cohort and maternal/infant/environmental measures as described in Project 1, meconium from known teetotalers and random meconium from our well baby nursery. These studies will provide preliminary data on the feasibility and utility of meconium analysis to gauge the influence of environmental neurotoxicants on human fetuses.